I copied and pasted this from Blogger support:
Add two CNAME records. For the first CNAME, where it says Name, Label or Host enter "www" and where it says Destination, Target or Points To enter "ghs.google.com" . For the second CNAME, enter "7BZEI5OEQTG3" as the Name and
"gv-B3LS74L6FYAQRVNL62C37GBEBMVF7VA7EDTW6ZMYHCKYAHEEAKLA.domainverify.googlehosted.com." as the Destination. See our detailed instructions on providing CNAMEs for various registrars. If yours isn't listed, or if you run into other difficulties, contact your registrar directly and they can help you out.